1. Field of the Invention
The present invention relates to a golf club, and in particular, to an improved head thereof.
2. Description of the Related Arts
In general, it is desirable to transmit the kinematic energy of a club head to a golf ball at the moment of impact, as effectively as possible, in order to increase the distance of flight of the ball. However, since both the ball and the club head are elastic, especially in a wide sense for the latter, elastic damped oscillation takes place on a club face and a ball surface, in accordance with eigentones thereof. Accordingly, if the eigentones of the face of the club head is lower than that of the ball, the elastic deformation of the ball is restored earlier than the restoration of the elastic deformation of the face of the club head which takes place at the moment of impact, so that the ball undesirably separates too early from the face of the club head. This results in an incomplete transmission of the restoration energy of the face of the club head, which elastically deforms at the moment of impact, to the ball, thus resulting in a loss of an initial velocity of the ball.
Japanese Unexamined Patent Publication (Kokai) No. 60-139267 discloses a golf club head having thereon a face insert having an eigentones substantially identical to that of the ball. However, in the club head disclosed in the publication, the eigentones of the face insert is made identical to that at the ball, an elastic damped oscillation of the face insert takes place under the influence of the eigentones of the remaining portion of the club head which usually has an eigentones frequency lower than that of the face insert.
Generally speaking, the lighter the wieght of a material, the larger the eigentones thereof, and accordingly, it is deirable to concentrically locate the weight portion of the head, as close as possible to a rear portion of the head, so that the face of the head is lighter, in order to minimize the possible influence of the eigentones of the head portion other than the face insert given to the elastic damped oscillation frequency of the face of the head.
However, in the prior art, since the head portion other than the face insert is made of a same material, it is not possible to satisfactorily concentrate the weight distribution of the head in the vicinity of the rear portion thereof.